[ExI] Maximum biological lifespan
anders at aleph.se
Fri Aug 12 06:54:51 UTC 2016
On 2016-08-12 00:16, David Lubkin wrote:
> Do you see any inherent maximum active lifespan (that is, not in a
> dormant state like a spore) for an evolved biological being?
Given how evolution works, multicellular organisms are likely but not
guaranteed to age - once they have reproduced their importance to the
eventual success to their genotype goes down drastically, so evolution
does not prevent accumulation of mutations that mess them up later
(=ageing). But as demonstrated by lobsters and some other organisms
(sturgeon?) there is no reason why ageing might not occasionally fail to
develop. Of course, the actual lifespan of non-ageing organisms is often
more dominated by being killed by predators, accidents and disease:
getting old enough to age significantly is a rare occurrence in nature.
So, no, there is no inherent maximum beyond the survival of the
ecological niche the being lives in.
> How about for a conscious evolved biological being (that is, with
> considerations of memory formation)?
A forgetful neural network can keep on learning forever.
> For instance, could there be a planet somewhere that naturally
> developed a single, continual consciousness that has lasted a thousand
> years? A million? A billion?
Perhaps. But it is not likely.
Remember that actual animal lifespans follow a fairly simple scaling law
with body mass, L ~ M^0.15 to M^0.3. (e.g. see
http://jeb.biologists.org/content/208/9/1717.long ) That might well be
an univeral rule of thumb, an attractor state that comes about because
of the tradeoffs between metabolism, time to build a body of a certain
size, and reproduction. If so, then it might hold true for most alien
Of course, that scaling suggests that *very* large creatures could fit
your demand. A thousand ton creature living for a thousand years doesn't
sound too far-fetched, assuming it makes ecological sense and lives in a
liquid environment (there is an upper limit to land animals because of
the square-cube law).
(To get to a million year lifespan the scaling requires about 10^16 kg
mass, about the same as the entire Earth biosphere. That sounds unlikely.)
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
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